This is the 14717th most frequent Polish word.
półfinalistek
"Female semifinalists."
In this sentence, "półfinalistek" is used in the genitive plural form of "półfinalistka" to indicate the group of individuals who reached the semifinals of the contest.
Półfinalistek konkursu piękności było dziesięć.
There were ten semifinalists in the beauty contest.
Here, "półfinalistek" is in genitive plural and part of a prepositional phrase indicating selection from the group of semifinalists.
Przyznano nagrodę jednej z półfinalistek.
An award was given to one of the semifinalists.
In this context, "półfinalistek" is in the genitive plural used to describe the group of female semifinalists whom the subject interacted with.